Obstructive sleep apnea (OSA) is a common medical condition that is characterized by repeated upper airway obstruction during sleep, despite efforts to breathe. Upper airway patency, normally maintained by afferent sensory input to cranial nuclei and efferent output to the upper airway, is altered in OSA. Patients often stop breathing hundreds of times during the night, limiting the amount of oxygen delivered to the brain and rest of the body. These pauses in breathing may eventually increase risk for stroke, myocardial infarction, arrhythmia, heart failure, and premature death. According to the National Heart, Lung, and Blood Institute, at least 1 in 10 people over the age of 65 suffer from sleep apnea. Other statistical measures demonstrate that approximately 2-4% of the adult population of the United States suffer from sleep apnea. Productivity losses associated with daytime sleepiness are significant and, as such, the economic burdens associated with sleep apnea are steadily increasing, thus making OSA a major public health concern.
In addition to obstructive sleep apnea (OSA), central sleep apnea (CSA) is another common form of sleep-disordered breathing. Central sleep apnea results from recurrent complete or partial absence of respiratory effort and can be caused by impaired respiratory control at the level of the medullary reticular formation. Although in the general population the prevalence of CSA is lower than that of OSA, patients with disorders such as MS that affect the brainstem may be at increased risk for CSA or apnea-related sudden death. Cases of both obstructive and central sleep apnea in structural and ischemic brainstem syndromes are well documented.
Accordingly, diagnosing and treating sleep apnea is important because of its strong association with and potential cause of several serious medical conditions, such as hypertension, cardiovascular disease, coronary artery disease, insulin-resistance diabetes, depression, and sleepiness-related accidents. Sleep apnea is a treatable risk factor for cardiovascular disease, motor vehicle accidents, fatigue, and decreased quality of life.
Current treatments for sleep apnea are cumbersome and physically intrusive, such as administering continuous positive airway pressure (CPAP), which involves wearing a mask every night to splint the upper airway open during sleep. Some patients have surgery to treat their obstructive sleep apnea, and others use an oral appliance nightly.
Currently, there are no effective pharmacologic treatments for obstructive sleep apnea. Consequently, drugs for treating sleep apnea will be life-altering to many throughout the world.